Nailing aerocrete and method of producing the same



Patented May 3, 1932 CARL J. LARKINS, OF NEW YORK,

" OF AMERICA, OF

N. 'Yf, ASSIGNOR we ran moqmn ooaroaa'rmn YORK, n. Y., a eonromrron' or DELAWARE nunmamnoonnrn AND nnrnon or 'rnonnonw R Drawing.

, My invention relates'to an improved '0- rous concrete or so-called aerocrete, capa le of holding nails driven into the same and to a method of making the improved product.

Porous concrete is made according to .the

method disclosed in' U. S. Patent No. 1,087

098, dated February 14, 1914, granted to Aylsworth and Dyer. According t0' said patent a cement mixture, with Water, is Sub ected to expansion caused by the development of gas therein due to the dissociation of the water, b means of powdered aluminum,

powdere aluminum alloys, powdered zinc or in any other suitable and convenient way.

Usually a small amount of lime is added to facilitate the'r'eaction and a suitable aggregate such as sand may be employed. In this way a porous body is obtained. consisting to a large extent of small uniformly distributed cells and possessing desirable commercial a dvantages due to its cheapness, lightness, and firZ-proofing qualities.

though nails can be driven into the po-- rous cement or concrete as so formed, the fragile nature 'p or holdon the nails which therefore can easily' ulled out. Porous concrete has found wi e use. as a material for roofing slabs due to its lightness, insulation value, 0 and considerable strength when reinforced. It is not racticable, however, to expose the surface of the porous concrete to the influence of weather-owing to the fact that water is partly absorbed resulting in surface disintegration. For this "reason when 'the material is 'employed'for roofing purposes, it is the. practice to cover and protect the surface in some manner, as for instance, byapplying shingles or sheets of copper or other weather resisting materials that will prevent the absorption of water. v

It has heretofore been necessary to' apply an intermediate 1a. er of semi-plastic mate-- rial, capable of hol ing nails driven into it in order that the shingles, copper sheets, or other protective covering ma be satisfactorily and permanently applied on top of'the roof. This separate operation is costly and increases the weight of the roof unnecessarily.

of the latter prevents a firm' sired. Also in order that exact Application filed June 98, 1980. Serial No. 484,708.

The present invention consists of a method of making and an improved product com-- prising precast slabs of porous concrete into which nails can be driven and held firmly in place, thus lpermittindg an outer protective covering. to e applie permanently thereto. In carrying out my invention inpractice, I use a mixture of one part of Portland or other hydraulic cement, one to two parts of ordinary mortar sand and add thereto from one-fifth of one part to two'parts of wooden shavings by volume, together with the necessary water. To this mixture is added a small quantity of powdered aluminum or powdered alloys of aluminum and zinc, aluminum and tin or zinc and tin as indicated in the patent to Aylsworth and Dyer above identified; If desired, asmall proportion of free lime can also be emplo ed. Owing to t e reaction between the metal powder andthe alkaline constituents in the mix, the water will be dissociated and hydrogen bubbles developed which in expanding will result in the pr u'ction of small substantially uniform cells in the mass in very much the same way as the action of yeast in causing dolirgh to rise. The proportions above given are ustrative only and may be substantially varied according to the product deit will be understood that the expansion of the mass maybe effected in other wa s now known to the art.

n the practical manufacture of porous concrete or aerocrete as nowpracticed the mass is allowed to expand over the tbp of the mold or form andwvhen the mass has taken its initial set, the surface-is then screeded off by means of a straight ed e or other suitable tool mensions may be obtained and a smooth continuous surface be secured. However, if this usual method were employed with a mix containing shavings the result would be that the screeded top surface would be rough and weak, making it an unsuitable base for nailing since the shavings from the to layer would be pulled up from the concrete by the action of the straight edge.

order to avoid this,

and by means of a roller the material expanded above the edge adhesion of the same to the roller.

\ or the like covering employed on top as apro I of the form or mold is pressed level. In this way the upper zone of the slab will be compressed into a porous crust with a smooth finished top surace. 1 find it necessary to employ a sheet of paper on top of the mass in order to prevent S111 sufliable ade of paper ma be employe cient y strong and flexi ace to facilitate subsequent removal.

The operation of thus compressing the top 7 surface of the slab is performed when the imtial set of the cement, concrete or aerocrete has taken place,

tion is from two to four hours after the exanded concrete has been poured. After rolling, as exp1ained,the sheet of paperis removed. 1

By pressing the top layer into a hard surface a suitable base for nailing is obtained due to the fact that nails driven mto the wooden same way as when shavings are held in the the shavings are driven into solid wood, since firmly sustained-within the layer of com-.

'pressed concrete. At the same t1me a smooth even surface of the slab is securedm suitable as a base for shingles, copper s tective coating. 7

has

asv

inate to such anextnt' as ings, the ma or portion of w and above Instead of employingwood shavings other fibrous, material ma be used such as asbestos, sugar cane fibre, an other fibres of ve table origin. In using the expression woo shavings in. my clalms, I wish to have the same understood as comprehending wood shavings erse or other equivalent vegetable or mineral bres'. Wood shavings however, are pre ferred on account of the r cheapness and desirable physical characteristics. I

described my, invention what Having now I claimis new therein is as follows 1. As a new article of manufacture a orous concrete ich product contains numerous cells or pores and the top layer thereof being dense and non-porous and in which the wood shavings predominate to such an extent as to hold nails driven therein.

2, The process of making nailabl'e porousv cement or concrete products whichconsists in introducing a; mixture of hydraulic cement,

and an aerating agentv in a wood shavings, form or mol ,;permitting the the moldor form so as to mixture to ex result in the production of pores or cells therein and finally com formahar inte alsubstantially non-porous top layer in whic the wood shavmgs predomto permit nailing; ARLv J. LARKINS.

hard strong substantially nonle for the purpose, refer-ably having a smooth calendared surbut before the actual harden- I ing has commenced. It has been found that themost suitable time to perform this opera aking it beets product containiri wood s avressmg the expanded mixture to 

